AirHint found the following cheapest return flights from Washington (IAD) to Madrid (MAD) in December 2025 (see full year).

Return flights

08 Dec - 15 Dec	Lufthansa
02 Dec - 09 Dec	British Airways	direct
10 Dec - 09 Jan	Air Canada
02 Dec - 16 Dec	Delta
10 Dec - 16 Dec	KLM
04 Dec - 11 Dec	British Airways	direct
03 Dec - 07 Dec	British Airways
28 Dec - 08 Jan	Lufthansa
01 Dec - 08 Dec	Delta
04 Dec - 08 Dec	SWISS
29 Dec - 12 Jan	Lufthansa
05 Dec - 12 Dec	Iberia
11 Dec - 18 Dec	Iberia
30 Dec - 24 Jan	KLM
25 Dec - 17 Jan	KLM
26 Dec - 17 Jan	Lufthansa
30 Dec - 07 Jan	SWISS
23 Dec - 12 Jan	Air Canada
22 Dec - 17 Jan	SWISS
15 Dec - 10 Jan	SWISS

Also check the deals for one-way flights from Washington to Madrid in December.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Washington to Madrid in December from 356€

Return flights