Invoices in business have terms of payment. Besides of due date, it may also have information on a discount, if the invoice is paid before the due date. Terms of payment may have high importance in a company's liquidity.[br][br]Terms of payment includes[br][list][*]discount percentage, if the invoice is paid in upon given time period[/*][*]the due date, and[/*][*]penalty interest, if the invoice is paid after the due date.[br][/*][/list]The dates are calculated by [b]real days/360[/b]. [br][br]Invoices must always include information on penalty interest (p.a.) and its starting date. The penalty rate is paid from the following day of due date till the actual date of payment.

An invoice of 840.00 euros is dated October 7. Terms of payment are "14d -2%, 30 d netto, penalty rate 8%".[br][br]a) The last date for the discount is October 21. They have 14 days time for the discount: 7 + 14 =21. The payment would be 98% of the original payment, that is[br][br]  [math]\Large 0.98\cdot 840.00€=823.20€.[/math][br][br]b) The last date for payment of 840,00€ would be at 30th day after the marked date. The rest of October is 24 days. Thus in November, there is still 6 days to pay the invoice in netto. The due date is November 6. [br][br]c) Penalty rate is calculated from the due date forward. If the invoice is paid December 15, so [br][br][table] [tr][br] [td]November: [br][/td][br] [td]30-6=[/td][br] [td]24[/td][br][/tr][br] [tr][br] [td]December:[/td][br] [td][br][/td][br] [td]+15[/td][br][/tr][br] [tr][br] [td]Total[/td][br] [td][br][/td][br] [td]=39[/td][br][/tr][br][/table][br]Penalty rate is [br][br]   [math]\Large r =k\cdot i\cdot t=840.00\cdot 0.08\cdot\frac{39}{360}=7.28€[/math][br][br]The total payment would be [math]\Large 840.00+7.28=847.28€.[/math]

Residual tax of 3273.60 euros had the due date of Dec 4, but it was actually paid Jan 25. The penalty rate was 8.0%. How much is the penalty rate and how much was actually paid?[br]Penalty rate must be paid for (30 - 4 =) 26 days in December and for 25 days in January. Thus, the penalty rate is[br][br]  [math]\Large r = k\cdot i\cdot t=3273.60\cdot 0.08\cdot \frac{51}{360}=37.10€ [/math][br][br]Thus, the actual payment was [math]\Large 3273.60€+37.10€= 3310.79€[/math][br][br]